The invention relates to stick-deodorant or the like containers wherein the deodorant substance is loaded against a piston within the bore of an elongate housing, and wherein a base-operating member is exposed for rotation at the lower end of the housing and drives the piston via an upstanding threaded stem which is part of the base-operating member.
The deodorant or the like substance which must be loaded into such a container is melted by heat and poured as a liquid into the open upper end of the housing, being thereafter allowed to solidify into a stick, upon cooling to ambient temperature. The melted substance is of low viscosity and therefore has a tendency to leak through the region of stem-thread engagement to the piston, so that various measures have been adopted to minimize the involved loss of dispensable substance and the unsightliness of substance that may have exuded via clearance needed for rotary actuation of the base-operating member.
Among the techniques adopted to reduce such leakage is to design the thread engagement to be full at and near the down-position limit of the piston, and to provide for ratcheting engagement of the piston to the lead screw or stem when in the down-position limit, the ratchet engagement being desired to assure against inadvertent piston displacement due to vibration in the course of handling and transportation, from the container manufacturer to the filling house. Typically, the ratchet formations may have an angular distribution of six teeth poised for axially confronting engagement at the down position of the piston, and the thread engagement may be characterized by a triple lead of 0.0625-inch pitch threads, meaning a piston advance of 0.1875-inch, for each full rotation of the base-actuating member. However, even with the indicated measures, and even with special provision for chilling the poured substance, there are such adverse combinations of departure from exact fit of the parts that leakages continue to plague the filling house.